Transmission of pictures by electricity



Jan. 11, 1927.

DE WlTT c. TANNER TRA NSHISSION OF PICTURES BY ELECTRICITY Filed Sept. 2131923 Patented Jan. 11, 1927.

UNITED STATES PATENT OFFICE.

DE WITT C. TANNER, OF GLEN RIDGE, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, 013 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TRANSMISSION OF PICTURES BY ELECTRICITY.

Application filed September 21, 1923.

This invention relates to the transmission of pictures by electricity and more particularly to means for reproducing a facsimile of the picture to be transmitted.

It is well known that pictures may be transmitted by electricity by varying an electric current in accordance with the picture to be transmitted and using this varying electric current to reproduce a facsimile of the picture.

An object of this invention is to accomplish the reproduction of such a facsimile in a simple and convenient manner.

Another object is to ,produce the facsimile in a form similar to an ordinary half tone.

Another object is to employ electric current transmitted over ordinary telephone lines for controlling the reproducing means.

In accordance with the general features of the invention, means are provided for transmitting current impulses, the character and strength of which are controlled b the gradations or variations in the density of the picture to be transmitted and amplifying these impulses to operate electroresponsive means for recording the picture directly upon a blank. The pressure of the recording'means upon the blank determines the character of the record.

The novel features which are considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method (if-operation together with further objects and advantages thereof will best be. understood by reference to the following description taken in connectionwith the accompanying drawing.

Fig. 1 is a schematicarrangement of one embodiment of the invention showing both the transmitting and reproducing circuit elements.

Fig. 2 is a side view of one type of reproducer.

Fig. 3 is a section along the line A-A of Fig. 2 showing in addition an inking roller and a partial outline of the receiving drum and blank. I I

Fig. 4 is an enlarged section through the reproducing roller and receiving drum and blank.

Fig. 5 shows another type of reproducer employinga penpoint instead of a roller.

In the embodimentof the invention dis- Serial No. 663,981.

closed diagrammatically in Fig. 1, the trans mitter and receiver each comprise a rotating cylinder 5 driven by a motor 6 at substantially the same speed through a slip friction clutch 7. The rotating cylinders are caused to travel axially in any suitable man ner.

The photographic film or picture to be transmitted is wrapped around the transmitting cylinder. Around the receiving cylinder is wrapped a blank or sheet of paper upon which a facsimile of the transmitted picture is to be recorded. The film or picture to be transmitted and the recording sheet are held in place around the cylinders suitable fastening means, for example, a c 1p.

The transmitting cylinder 5 is of glass and light from a source 8 is directed upon a photoelectric cell 9 by means of a lens 10. The beam of light from the source 8 converges at the surface of the cylinder 5 so that the light admitted to the photoelectric cell 9 passes through a particular spot on the film which, at the time, is directly in front of the focal point.

While the cylinder 5is revolving, it is also moved axially with respect to the photoelectric cell 9 so that the scanning of the picture will trace a helical path around the cylinder and will completely traverse the picture.

The photoelectric cell 9 is connected to a vacuum tube amplifier and modulator 11, the output circuit of which is connected to a line '12. Current from the photoelectric cell 9, varied in ac(.'ordnnce with the gradations of the photographic film, may be transmitted as modulations of a carrier current from a source 13. The frequency of the carrier current from the source 13 may lie within the range of frequencies normally used for ordinary telephone transmissions and consequently carrier current may readily be transmitted over ordinary telephone lines. The modulated carrier current upon arrival at the receiving terminal may be amplified and detected by suitable devices, such as, electron discharge devices, located within the block 14.

Devices suitable for use at blocks 11 and 14 are disclosed in an application of A. M. Nicolson, Serial No. 205,993, filed December 7, 1917 patented October 16, 1923, No. 1,470,696.

The receiving reproducer comprises a solenoid l5 and printing roller 16 having a plurality of small compressible extensions on its periphery. The roller 16 is driven by friction rollers 17 through a flexible shaft 18. The printing roller 16 is kept inked by a suitable ink roller (not shown).

The friction rollers 17 are held continuously against the receiving blank mounted on the receiving cylinder 5 while the printing roller 16 is brought in contact with the printing blank by the action of the solenoid 15, the pressure of the printing roller against the receiving blank being dependent upon the strength of the current in the solenoid 15.

The mounting of the solenoid 15, printing roller 16 and friction roller 17 is shown more clearly in Figs. 2 and 3. The friction roller 17 and the solenoid 15 are mounted on a support 19 which is flexibly attached 'by means of a spring 20 to the framework 21 which is an integral part of the support for the revolving cylinder 5. Pivoted to the support 19 is an armature 22 which carries the printing roller 16 and ink roller 23. The spring 24 tends to hold the armature 22 in retracted position while the spring support 20 holds the friction rollers 17 continually against the printing blank on the cylinder 5. It is obvious that this arrangement prevents possible inaccuracies in the reproduced picture due to unpreventable chan es in the position of the record blank surrace at the printing point with respect to the framework 21. This change of position may be due to a departure of the record blank from true cylindrical form or to lost motion in the machine bearings or other moving parts.

The friction rollers 17 and the printing roller 16 are of the same diameter so that their peripheral speeds will be the same and consequently the peripheral speed of the printing roller will be the same as that of the printing blank on the receiving drum 5.

As shown in Fig. 4, the surface of the printing roller 16 carries a plurality of small compressible extensions 25. These extensions are preferably of circular cross section and shaped as shown in Fig. 4. As the cylinder 5 revolves carrying the blank 26, a series of dots of varying sizes will be printed on the paper. The size of the dots will be dependent upon the pressure between the extensions 25 and the recording blank. 26. The

solenoid 15 which responds to changes in the strength of the received signals determines the pressure between the extensions 25 and the printing blank 26 and consequently the size of dot.

The resulting facsimile of the transmitted picture consists of an orderly arrangement of dots of different sizes similar to an ordinary halftone newspaper picture.

In the alternative reproducing arrangement shown in Fig. 5, the printing roller 16 is replaced by a pen 27. Variations in the current flowing through the solenoid 15 causes varying pressure between the penpoint 28 and the receiving blank on the receiving drum 5 through its armature 22. An ink line of varying width is consequently produced as the cylinder 5 rotates. A suitable means for mounting the pen and solenoid support 29 is obvious from the mounting of support 19 shown in Figs. 2 and 3.

The control or synchronization of the transmitting and receiving equipment may be effected over a separate line including a control relay 30 at each station. At the start of each revolution, the two cylinders are released sin'lultanemisly, neither cylinder being permitted to make more than one revolution or cycle of operation until the other cylinder has completed a corresponding revolution or cycle of operation, in which case the control circuit is closed and the release mechanism at each station is automatically operated to permit both cylinders to start on the next cycle. This method of control is not new and is disclosed in connection with many printing telegraph systems.

Other means of synchronization may be employed, for example, a system as disclosed in Rainey Patent No. 1,279,905, September 24, 1918. Instead of using a separate line for synchronizing purposes synchronism may be maintained by means of a. low frequency current impressed on the same transmission line over which the picture is transmitted. the synchronizing signals being separated at the terminals by suitable filters. Still another schemefor obtaining synchronization is disclosed in a U. S. application for patent of R. D. Parker, Serial No. 504.680, filed October 1, 1921.

\Vhat is claimed is;

1. In combination, a picture'to be transmitted, transmitting means to transmit current impulses varying in strength in accordance with the density of the picture, receiving means comprising a record blank, a record producing device in operative relation to said record blank, and means selectively responsive to impulses of varying strength to vary the degree of contact between said recordproducing device and said blank to produce a half-tone, facsimile of the transmitted picture.

2. In combination, a picture to be transmitted, transmitting means to transmit current impulses varying in strength in accordance with the density of the picture, receiving means comprising a record blank and a printing roller having compressible extensions thereon, and means selectively responsive to impulses of varying strength to vary the degree of contact between said extensions and said blank to produce a facsimile of the transmitted picture.

3. In a system for transmitting pictures by electricity, a picture to be transmitted, means comprising a photoelectric device for producing current impulses varying in strength in accordance with the density of the picture, and reproducing means comprising a record blank, a record producing device in operative relation to said record blank, and means selectively responsive to current impulses corresponding to said varying impulses to vary the degree ofcontact between said record producing device and said blank to reproduce the transmitted picture directly upon the record blank in the form of dots of varying sizes.

4. A reproducer for pictures transmitted by electricity comprising, a record blank, a record producing device, means to cause relative movement between said record blank and said record producing device, means to cause contact between said record producing device and said record blank at varying pressures to produce records of different character and means having movable contact with said record blank to maintain a definite distance between said record blank and said record producing v device during such time as no record is being produced.

5. A reproducer for pictures transmitted by electricity comprising, a record blank, a record producing device, means to cause relative movement between said record blank and said record producing device, means to cause contact between said record producing device and said record blank at varying pressures to produce records of difierent character, and means having movable contact with said record .blank to maintain a fixed relationship between said record blank and said record producing device during periods of record reception of nnvarying character.

(i. A reproducer for pictures transmitted by electricity, comprising a revolving record blank, a printing roller having compressible extensions on its periphery, means to cause rotation of said roller at a peripheral speed substantially equal to that of the surface speed of the record blank, and means to cause contact between said compressible extensions and said record blank at varying pressures.

7 A reproducer for pictures transmitted by electricity, comprising a revolving record blank, a printing roller having compressible extensions on its periphery, a friction roller contacting with said record blank and rotated thereby, a coupling between. said friction roller and said printing roller for pausing the rotation of said printing roller, and means to cause contact between said compressible extensions and said record blank at varying pressures.

8. In a system for transmitting pictures by electricity, the combination of a transmitting mechanism and a receiving mechanism, each comprising a rotatable cylinder, means for mounting on one oi said cyl1n-' ders the picture to be transmitted and on the other of said cylinders a blank on which the picture is to be recorded, a, photo-electrio cell associated with the transmitting mechanism, means for causing relative longitudinal motion between said cell and said cylinder while said cylinder is rotating, means for passing rays of light through the picture to the cell, amplifying means associated with the cell and responsive to current variations produced therein, a transmission channel connecting said amplify ing means and said receiving mechanism, said receiving mechanism comprising a rotatable wheel having compressible exten sions on the periphery thereof, means for producing relative longitudinal motion between said wheel and said rotatable cylinder, and means for bringing said extensions into engagement with said record blank with varying degrees ofpressure depending upon the strength of said transmission channel signals.

9.In a system for transmitting pictures by electr'icitv, the combination of a transmitting mechanism and a receiving mechanism, each comprising a rotatable cylinder, means for mounting on one of said cylinders a picture to be transmitted and on the other of said cylinders a blank on which the picture is to be recorded, a photo-electric cell associated with the transmitting mechanism,

means for causing relative longitudinal motion between said cell and said cylinder while the cylinder is rotating, means for passing rays of light through the picture to thecell, amplifying means associated with the cell and responsive to current variations produced therein, a line circuit connecting said amplifying means and said receiving mechanism, said receiving mechanism comprising a rotatable roller having compressible extensions on the periphery thereof. means for causing relative longitudinal motion between said roller and said rotatable cylinder, means for bringing said extensions into engagement with said record blank with varylng degrees of pressure depending upon the strength of the line signals, and

llti

means for maintaining synchronis'm between said rotating cylinders and between the relative longitudinal motion of said photoelectric cell and said rotating roller.

10. In a system for transmitting pictures by electricity, a rotatable cylinder, means for mounting on said cylinder the picture to be transmitted, a photoelectric cell associated therewith, means for causing relative longitudinal motion between said cell and said cylinder while the cylinder is rotating, means for passing rays of light. through the picture to thecell to produce current variations therein, amplifying means responsive to said current variations, recording means comprising a rotatable cylinder and a rotatable roller having compressible extensions on the periphery thereof, inking means for said extensions, a transmission channel connecting said amplifying means and said record ing means, a record blank attached to said cylinder, and means for bringing said extensions into engagement with said recording 10 blank with varying degrees of pressure, said means being responsive to variations in strength of the transmitted signals.

In witness whereof, I hereunto subscribe my name this lath day of September A. D.,

DE WITT C. TANNER. 

